In the early morning of 15 September 2018, Typhoon Mangkhut (locally named Ompong) made landfall in Baggao, Cagayan, in northern Luzon as a Category-5 typhoon. The typhoon caused widespread flooding and multiple landslides. High winds destroyed homes and crops and left vital infrastructure damaged. Prior to the disaster, an impact analysis conducted by OCHA estimated that 4.6 million people were living in areas potentially affected by the disaster. As of 20 September, over 1.4 million people in 31 provinces in Regions I, II, III, IV-A, IV-B, the Cordilleras Administrative Region (CAR) and Metro Manila had reportedly been affected by the typhoon.

Prior to the typhoon, local governments pre-emptively evacuated 152,000 people in Regions I, II, III, IV-A, V, CAR and Metro Manila from their homes to evacuation centres. By 18 September, more than 236,000 people had been displaced by the disaster, with over 162,300 people seeking shelter in at least 1,780 evacuation centres, and more than 73,600 people staying with host families. Many of those displaced began returning home or to host families by 19 September.

As of 20 September, it was reported that almost 44,600 houses had been damaged including more than 3,600 houses that had been destroyed. This number is expected to continue to rise. The houses most vulnerable to the typhoon were those constructed from light materials, of which there are an estimated 202,000 such buildings in the four most-affected regions. While the national authorities have confirmed eight deaths, 21 injured and two missing in Regions I, III, CAR and Metro Manila as of 19 September, they are still validating at least 55 other deaths. The media, citing various national authorities, have reported at least 100 deaths, mostly due to landslides.

The areas most severely impacted by Typhoon Mangkhut are Regions I, II, III and CAR in northern and central Luzon. The full extent of the impact is still unknown as many locations remain inaccessible due to landslides, power cuts and disrupted communications. The number of casualties, damaged homes and people affected are expected to increase as debris clearing progresses and isolated areas become accessible.

The regions affected by the typhoon are predominantly agricultural, with at least 2.3 million people engaged in employment in the agricultural sector. The region is a major producer of rice and corn, and the country is facing an ongoing rice shortage.

Prior to the typhoon, there were already a number of pre-existing vulnerabilities that are likely to have left people especially vulnerable to the impacts of the typhoon, including about 15 per cent of the population living below the poverty line, approximately eight per cent of the population relying on dug wells or natural sources for water and on pit latrines for sanitation, higher-than-average rates of malnutrition among children less than 5 years old, and vaccination rates of 60 per cent or lower, based on data shared by the Department of Health.